Mine-prop.



J. H EICKERSHFF.

MINE PROP.

APYLICATION FILED JULY 13,1009.

969,85 1 Patented Sept. 13, 1910.

Fi Gl- Fi G.5,A-B. Fizw Y. To all whom 'itmcy concern:

saar-Es PATENT onirica.

Specification otLetters Patent. 'Patented Sept. In, 19in.

Application ined my 1s, 1909. serial No. 502,374.

Be it known that I, J oHN H. Eicimiisorr, 'a citizen of the United States, residing at Dusseldorf, Germany, have invented new and useful Improvements in Mine-Props, of which the following is a specilication.

This invention.- relates to a mine prop.

composed of a lower tubular member containing a granular charge and of an upper tubular .member telescoped by the lowery member and supported by said charge. The construction is such that as the u per member isforced intothe lower member by the load pressure, the area of the pressure bearing surface presented by the upper member to' the granular charge is gradually increased,

and that an increase ofsuch pressure must take place prior to any subsequent change in the length of the prop.

' In the accompanying drawing: Figure 1 isa longitudinal section of my im roved .mine prop; Fig. 2 a similar section t rou h `part of the prop, showing the parts in a diferent position;.Fi 3 a cross section on 1g. 4 a cross section on hne CD,'F1g. 2; F1 5 a cross section on line'E-F, Fig. 2; ig. 6 a' longitudinal. 'section of a modification of the prop; and

7 a cross section on line (Et-H, Fig. 6. he prop is composed essentially of a lpair of telescoping tubular members a, b,

' of; which the lower member b,"is filled with .of member a, will rest upon the surface o .the sand m, contained in member b. U on a I charge of sand or similar granular material. Within the lower end of upper member a,

iare litted a number of braces shown to con- .and traversing member a, in 'different diametric directions. In its initial position the lower edge a lv-.Zaiiincrease lof pressure, member a, wil be 4forced'into the sand until lthe lowermost -tof'fbrace' 82. Thus, itwill be seen that the area of the pressure'bearing surface is ilicreased by a ,descent fof the u per prop.

member, and that an increase ofc' cad` ressure must take place before the lengt of the prop is changed.

Lower member b, is supported upon 1 the false bottom late of a hollow -ot c. The upper en of oot 0,; encompasses 'the lower end of member b, and is of such a 'ameter as to, form an intervening recess adapted for the accommodation of an annular valve-r. This valve is provided with openings 1", adapted to register simultaneously with dianl'etricall arranged outlet openings o,` offmember l? and with inlet openings p', of plate p. -Wzhen valve 17, .is so turned b its handles '72, that communication is established between the interior of` mem# ber VI) and the interior of foot c, the sand will dow from the former into the latter, thus shortening the pro to 'such an extent that it may be readily re eased from its supporting position. U on tilting the rop upside down, the san may be` ma e to reenter member b, so that any waste of .`sand is revented. l n Figs. 6 and 7, a tubular sleeve l1., is

fitted into lower 'end of member a, so as to project into member b' and nd a bearing upon the sandwith its lower edge Sleeve h, has a Harige g, engaged by mem ra, and a shoulder f that 'constitutes an additional bearing surface` adapted to come into' action after ythe sleeve has been partly pressed into the sand. Above shoulder f', the sleeve is provided with the superposed diametrcally extending braces a', c2, a",y previously described.`

-I claim:

A mine prop com 'alower tubular member,A an inclose granular charge, an upper tubular member telescopedy by the lower member, and a'series of spaced superposed braces extending diametricallyacross the upper member and adapted tosuccessively enter thecharge.

JOHN H. EICKERSHOFF. Witnesses:

Ims VANDORF, Mrs. H. J. Dimm. 

